This invention relates to the mixing of fluids and, more particularly, to a motionless mixer apparatus which operates on a multiple venturi principle.
In industrial mixing two or more materials are blended together to yield a homogeneous product. Devices that employ propellers or turbines to cause mixing by agitation are quite common. These "dynamic" type mixers, while quite effective, involve the use of power driven elements and other moving parts which tend to make them relatively expensive to manufacture, install, operate and maintain. Motionless or "static" mixers are advantageous in that they have no moving parts, but mixing action is not always adequate. The simplest device of the static type is a straight length of pipe 50 to 100 diameters in length. Various more complicated static mixers are described, for example, in U.S. Pat. Nos. 2,025,974, 2,784,530, 3,051,453, 3,239,197, 3,286,992, 3,459,407, 3,775,063, 3,908,702, 4,040,256, and 4,043,539.
In one well known type of mixer (see e.g. U.S. Pat. No. 3,286,992) a series of short helical divider elements are mounted in a pipe. Each helical element divides the fluid stream into two parts and causes it to rotate through 180.degree. before it is passed to the next element whose leading edge is oriented at 90.degree. with respect to the final edge of the prior helical element. For n elements there are 2.sup.n divisions and recombinations of fluid which is somewhat analagous to cutting a deck of cards 2.sup.n times. While this and certain other static mixers are capable of acceptable performance, the nature of the structures involved often does not lend itself well to inexpensive manufacture.
It is an object of the present invention to provide a static mixer which both exhibits good performance and can be fabricated relatively inexpensively from a minimum of parts.